Considerations for Selecting Dry Composite Adhesives

Dry compounding is the process of using a dry compounding device to bond two or more films together using an adhesive. The amount of adhesive used in dry compounding is small, accounting for about 10% of the material cost, but it has a very important influence on the quality of the composite film. It determines the peel strength of the composite film, and affects the transparency of the composite film, heat seal strength, heat resistance, resistance to media, etc., so the choice of adhesives for composite flexible packaging companies should be very cautious.

The selection of adhesives for composite flexible packaging should mainly consider the following aspects:

I. According to the requirements of the packaging product to choose the adhesive

1, after the packaging product after the processing temperature is different, the choice of adhesive will be different. For example, the common temperature classifications include steaming 135°C for 30 minutes, boiling for 121°C for 30 minutes, boiled for 30 minutes, 85°C for 30 minutes, room temperature, freezing, and deep freezing. In this regard, the soft pack factory should be very careful. If your product is 135°C for 30 minutes, you must use an adhesive that can meet this temperature requirement, such as Gaomeng's YH502/YH10; if your product only requires 121°C for 30 minutes. The cooking, you do not need to use 135 °C resistant adhesive, as long as the adhesive to reach 121 °C 30min is such as Gao Meng company's YH502S/YH10, otherwise choose to resist 135 °C adhesive is a waste, invisible The increase in your production costs.

2, according to the nature of the product package to use adhesive gas (inflated packaging)
Liquids: water-soluble, solvent-based, pH, solid solids in the wet: different from the packaging of products with volatiles and no volatiles, the choice of adhesive is also different. Such as mustard packaging must consider when the adhesive acid, spicy, salty and other patience; such as washing.

2. According to the structure of the composite packaging, the materials used for the adhesive composite packaging are various. Common materials include BOPP (light film, pearl film, matting film, etc.), PET, BOPA, AL, and yttrium aluminum film (VMPET, VMCPP, VMPE, etc.) CPP, PE, etc. The single PE film is very different. If the thickness of the PE is different and the resin used is different in the characteristics of the PE film, the selected adhesive is also different. For example, during the rolling process of aluminum foil, a release agent (oil) must be added. Although the aluminum foil has been cleaned after rolling, oil contamination still exists. Therefore, in the selection of adhesives for compounding, it must be considered that there is a certain degree of resistance to oil contamination, especially in the selection of high solid content adhesives.
In the composite aluminum film, the use of ordinary adhesive, the general peel strength is only 0. 3-0.6N/15mm aluminum transfer serious. If such a packaging bag is used to package some irregular solids (such as tea leaves) and then vacuumed, after a period of time, large white foam will appear on the outer surface of the packaging bag, that is, the outer layer of the aluminum-plated composite film will come off. Floor. Therefore, it is necessary to find a way to improve the peeling strength of the aluminized composite film (the adhesion strength of the aluminized layer before uncompositing is 2 N/15 mm), and to solve the problem of the transfer of the aluminized film, one of them is to use aluminum plating. Film adhesive special adhesive, such as Beijing Gao Meng Chemical Co., Ltd. Y H501S/YH10S or YH501SL/VM10 and so on.
In the aspect of composite PE film, if more PE additives are used for thicker additives, the precipitation of PE additives must be considered. If you do not pay attention to this problem, use an ordinary adhesive, then after the compound film is compounded, the peel strength will become lower and lower as the curing and time passes, and it will even be divided into two layers. Separated, due to lead in the compound high-adhesive content of PE film, you must be very careful to precipitate the problem of additives, use the adhesive to adapt to the adhesive. Such as Beijing Gao Meng Chemical's high-auxiliary film composite special adhesive series.

3. According to the use of dry composite equipment used adhesives Many composite flexible packaging companies will find such a phenomenon, the same kind of adhesive in different manufacturers with different effects. There are many reasons for this, and one of them is that the equipment used is different. There is a big gap in the grade of dry laminating machines used today. When selecting adhesives, adhesives should be selected according to the conditions of their own equipment.
Select the adhesive according to the tension system of the device's equipment. If the tension control system of the equipment is poor, the precision of the tension control is not high, and the tracking feedback is poor, then when selecting the adhesive, the initial adhesion should be good, so that the formation of the tunnel can be reduced and the yield can be improved. On the contrary, the tension control system is very good, so that the initial adhesive force of the adhesive is not bad, it does not matter, there will be no tunnel, and there will be no effect on the yield.
The adhesive is selected according to the working speed of the device. If the working speed of the device is high, then the viscosity should be selected when the adhesive is selected. If the viscosity is too high, the adhesive will generate a large amount of bubbles in the adhesive tank. Seriously affect the adhesive coating state, and then affect the quality of the product. On the contrary, the working speed is lower, and when the adhesive is selected, the viscosity can be higher.

Fourth, according to the technical indicators of the adhesive selection of adhesives If the technical indicators of the adhesive range of change is small, indicating that the performance of the adhesive is more stable, more conducive to the soft package factory to control the quality of composite products. If an adhesive factory proposes that the viscosity of the solids content of 75% of the adhesive is between 4000 and 8000 mpas, this is a common adhesive, generally with a viscosity of 80000mpas, and its optimum working concentration is 30%. When the working concentration is 35%, the coating state of the adhesive deteriorates, affecting the product quality; the adhesive with a viscosity of 4000m pas, the optimal working concentration is 35%, if the working concentration is reduced to 30%, then The cost increases, affecting residual solvents and production efficiency.
In addition, if the solid content changes greatly, the amount of adhesive applied will be affected.

5. According to the working concentration of the adhesive, the adhesive is selected. Under the same speed and other process conditions, the greater the working concentration of the adhesive, the more economical it is, and the better the transparency and other quality factors. The higher the solids content, the higher the working concentration of the binder. A 50% solids binder has a working concentration of 20% to 30%; and a 75% solids binder has a working concentration of 30% to 40%.

An example is given below (in the case of adhesive dry base: 3.0 g/m2):
Solution A: Use 50% solids binder, working concentration 25%, wet glue volume 12g/m2
Option B: Use 75% solids binder, working concentration 40%, wet glue volume 7.5 g/m2
Scheme A consumes 4.5 g/m2 of ethyl acetate, which is approximately 0.0315 yuan/m2, more than scheme B. If this 4.5 g/m2 ethyl ester is completely volatilized, it must consume a certain amount of heat and affect the production efficiency.
Therefore, when the adhesive is selected as high solid content as possible, the use of the highest possible working concentration, only with very good economy, can improve efficiency. At the same time, the transparency of the composite film will be better.

6. According to the choice of adhesive manufacturer, adhesives are nowadays many manufacturers of adhesives. The era of oversupply is long overdue. When selecting adhesives, you should also see how much the company can provide and how much technically stand by. The current social division of labor is more meticulous, and related industries can provide certain support services in the vertical direction, which will play a significant role in the development of the company.
Now that the market is in shape, it is no longer just a mere commodity exchange. It also attaches support, services, and brand image. Behind the tangible transaction, how many intangible supports and services are there?

7. According to the food hygiene performance of the adhesive, if the adhesive is selected as the food packaging, the food sanitation performance of the adhesive must be taken into consideration when selecting the adhesive, and if there is any odor. Otherwise, some unhygienic factors in the adhesive, such as odors, will penetrate into the food, and the resulting losses and effects are incalculable.
In summary, the flexible package plant should consider the packaged product, the structure of the composite material, the condition of the dry laminating machine, the technical indicators of the adhesive, the working concentration, the manufacturer, the food hygiene, etc. Many factors.